The present invention relates to a rotation angle detecting apparatus that highly accurately detects a rotation angle.
In the industrial machines, the surveying instruments, and others, a rotation angle detecting apparatus that detects a rotation angle is provided in a rotation unit. Nowadays, a highly accurate and small rotation angle detecting apparatus is demanded for these machines or instruments.
In general, as a rotation angle detecting apparatus used in a surveying equipment, an encoder is adopted, and a highly accurate encoder is expensive. Further, in order to improve a rotation accuracy of a rotation shaft to a required accuracy, just managing a machining accuracy for each individual component is difficult, the fine adjustment and the precision finishing in an assembled state of the rotation shaft and a bearing holder are required, which results in a very high price.